Metal-working tool



Jan. 15, 1946. a E 2,392,821

X METAL WORKING TOOL Filed Jan. 22, 1944 INVENTOR MaZwZm 6110609 ATTOR YPatented Jan. 15, 1946 METAL-WORKING TOOL Malcolm G. Kreag, Chicago,Ill., assignor to Haynes Sellite Company, a corporation of IndianaApplication January 22, 1944, Serial No. 519,323

6 Claims.

This invention relates to metal-working tools,

and refers more particularly to tools of the type used in working ordeforming hot metal, for example piercing points, hot-forming dies andthe like. For conciseness the invention will be described withparticular reference to metal-piercing tools. a In the manufacture ofseamless steel tubing and tubular articles such as shells and the like,a hole is formed in a hot steel billet by forcing a piercing point intothe billet, usually along the central longitudinal axis of the billet.The temperature of the billet is high, and the pressure required toforce the piercing point through the hot metal is heavy. The piercingpoint is thus subjected to extremely rigorous conditions, and its lifeis quite short, failure usually occurring because of severe wear orcracking.

Attempts to provide piercing points having reasonably long life inservice have been made but have generally been unsuccessful. Oneproposal, that piercing points be hard-faced with the well knownwear-resisting cobalt-chromiumtungsten alloys generally used forhard-facing articles subjected to severe conditions of wear, provedespecially disappointing, points hard-faced with these alloys failingafter a short time by cracking and partial loss of the surface layer ofalloy.

It is the principal object of this inventionto provide metal workingtools of the type used in working or deforming hot metal and subjectedto pressure, such as piercing points, which have a longer life inservice than those tools heretofore known and used. g

This object is achieved by the invention which comprises a metal-workingtool having a surface composed of a nickel-base alloy containingmolybdenum and chromium and is based on the discovery that a tool havingsuch a surface has a life several times longer than the life of othertools used in the same service. This discovery is surprising because thealloy used, developed and long used for resistance to corrosion byacids, has never been considered as having the properties required ofwear-resistant materials.

In the accompanying drawing the single figure is an elevational view ofa specific type of tool embodying the invention, part being broken away.

Although the tool of the invention may be composed wholly of thenickel-base alloy, for reasons of economy it is preferred that the bodyof the tool be composed of a cheaper metal and that a layer of the alloybe deposited on the wearing surfaces of the tool, suitably by welding.The

single figure of the drawing illustrates the application of theinvention to a piercing point P. The

body of the point P is composed of steel, and its wearing surfaces areprotected by a layer of a nickel-molybdenum alloy deposited thereon.

The alloy surface of the tool of the invention is composed of anickel-base alloy containing 5% to 25% molybdenum, 10% to 30% chromium,about 0.1% to 1.5% carbon, the remainder prin cipally nickel. The alloymay, and preferably does, contain up to about 10% tungsten, and iron maybe present as a diluent up to about 35% of the alloy, but the nickelcontent should exceed 30%. A composition that has given excellentresults. is 15% t 18% molybdenum, 13% to 16% chromium. 4% to 6%tungsten, 5% to 8% iron, 0.1% to 0.2% carbon, and the remainder nickel.The nickel content is most desirably at least and between about 55% andFor most purposes the molybdenum content should be at least 10%, thechromium content'not exceeding about 20% of the alloy.

In manufacturing the tool of the invention a tool body is preferablymade of a plain carbon or low alloy tool steel, and protective layers ofthe nickel-base alloy are formed on the wearing surfaces of the tool byfusion-deposition welding using either oxy-acetylene or electric weldingmethods. A preferred method of forming the protective layers is metallicarc welding. Only a relatively thin layer of the alloy need be applied.In welding, a welding rod having a composition within the ranges definedabove is used. The deposit produced from the welding rod may differsomewhat in composition from the composition of the rod due to dilutionof the weld metal with base metal, but care should be taken to avoid unnecessary dilution of the deposited weld metal. A

The weld-deposited metal is usually machined or ground to desireddimensions.

Tests of the tool of the invention have proved it to have several timesthe life of other tools used in the same service. As a specificillustration both of its serviceability and of its construction, thefollowing example is given.

A water-cooled piercing point 3 /6 inches in diameter and 25 inches longcomposed of a steel recommended for use in hot working metals wasprovided with a protective layer of a nickel-base alloy deposited bymetallic arc welding from a welding electrode composed of a nickel-basealloy having a composition within the preferred ranges above defined.The pointed end of the tool was covered with a protective layer for adistance of 8 inches from its tip, the layer being about I;

inch thick except at the tip where a deposit about inch thick wasformed. The tool so prepared was then used for piercing shells inaccordance with standard commercial practice. After the tool had beenused to pierce 420 shells, it was examined and found to be still usablewithout repair whereas substantially identical tools notprovided with aprotective layer were badly worn after piercing only 80 shells.

From this example it is evident that tools having surfaces composed ofthe nickel-molybdenumchromium alloy described have several times thelife of similar tools having unprotected surfaces.

The particular alloy used in the invention has been known and widelyused for many years in applications where advantage is taken of itsexcellent resistance to corrosion. However, because of its relativesoftness and low malleability and ductility and because it is workableonly with difficulty it has never been advocated for use as awear-resistant material. That it acts so well as a protective layer inthe extreme service encountered by the tools of the invention,conditions so severe that the commonly-used special wear-resistantalloys fail, is most surprising.

Although specific details of construction of a specific tool have beengiven herein, such details are for illustration merely and the inventionis not limited either to such details or to specific types of tools, butis generally applicable to tools used for working hot metal while thetools are subjected to pressure.

I claim:

1. A metal-working tool having a wearing surface composed of anickel-base alloy containing 5% to 25% molybdenum, to 30% chromium, theremainder principally nickel, the nickel content being about 55% to 60%.

2. A metal-working tool having a wearing surface composed of anickel-base alloy containing 10% to 25% molybdenum, 10% to 30% chromium,an efiective amount up to 10% tungsten, 0.1% to 1.5% carbon, theremainder substantially all nickel and iron, the nickel content beingmore than 30% and iron being present as a diluent in an amount up to35%.

3. A metal-working tool at least the wearing surfaces of which arecomposed of an alloy containing 15% to 18% molybdenum, 13% to 16%chromium, 5% to 8% iron, 4% to 6% tungsten, and 0.1% to 0.2% carbon, theremainder substantially all nickel, the nickel content being about to ofthe alloy.

4. A tool for deforming hot metal, said tool having a steel body portionand a protective layer, on at least its wearing surfaces, of an alloycontaining 15% to 18% molybdenum, 13% to 16% chromium, 5% to 8% iron, 4%to 6% tungsten, and'0.l% to 0.2% carbon, the remainder substantially allnickel, the nickel content being about 55% to 60% of the alloy. 4

5. A tool for deforming hot metal, said tool having a wearing surfacecomposed of anickelbase alloy containing 5% to 25% molybdenum, 10% to30% chromium, the remainder substantially all nickel.

6. A tool for deforming hot metal, said tool having a steel body portionand a protective layer, on at least its wearing surface, of an alloycontaining 10% to 25% molybdenum, 10% to 30% chromium, an effectiveamount up to 10% tungsten, 0.1% to 1.5% carbon, the remainder substantially all nickel and iron, the nickel content being more than 30%and iron being present as a diluent in an amount up to 35% MALCOLM G.KREAG.

